In general a silver halide photographic material comprises a support, such as a plastic film, paper, plastic-coated paper, glass or so on, and a combination of layers coated thereon which contains light-sensitive emulsion layers and other constituent layers chosen optionally from interlayers, protective layers, backing layers, antihalation layers, antistatic layers and so on.
The printing arts have recently required that operations be carried out efficiently and speedily, so that there is a comprehensive need for the scanning operation to be speeded up and for the processing time of a photosensitive material to be shortened.
In order to meet these needs in the printing arts, it is desirable for an exposure apparatus (including a scanner and a plotter) to increase its scanning speed, and further not only to increase the number of its scanning lines but also to converge its scanning beams to heighten image quality. On the other hand, it is desirable for a silver halide photographic material to have high sensitivity and high stability and to be quite suitable for rapid photographic processing.
The term "rapid photographic processing" as used herein refers to processing which takes 15 to 60 seconds for the top of a photographic film to travel from the insertion slit of an automatic developing machine to the exit of the drying part of the machine via the developing tank, the transit part, the fixing tank, the transit part, the washing tank and the drying part in succession, and the developing machine is operated at a line speed of at least 1,000 mm/min.
As a means for shortening the photographic processing time, it is effective to shorten the drying time by improving the drying characteristics of the silver halide photographic material to be processed.
In order to effect such an improvement in the drying characteristics, there may be adopted a method of reducing the binder content in the silver halide photographic material. However, this method has the disadvantages of lowering the mechanical strength of the silver halide photographic material, causing a blackening problem with scratches, causing roller marks, and so on.
The blackening problem with scratches is a phenomenon in which abrasion has occurred on the film surfaces during the handling of the silver halide photographic films before development and the abraded part is blackened in a scratch pattern after development. Roller marks are a phenomenon in which the pressure imposed on the surface of a silver halide photographic film during photographic processing with an automatic developing machine varies depending on the fine roughness of the rollers used in the machine to cause black spotted unevenness in photographic density.
Both the blackening problem with scratches and roller marks impair considerably the value of silver halide photographic materials.
In the case of a silver halide photographic material having all of its silver halide emulsion layers on one side of a support (abbreviated as "one-sided emulsion material" hereinafter), drying characteristics can be improved by removing the light-insensitive hydrophilic colloid layers from the back side of the support or by using a hydrophobic binder in the light-insensitive layers provided on the back of the support. However, these measures are still unsatisfactory, so that further improvements in drying characteristics are required.
On the other hand, there are automatic developing machines which are equipped with a drying operation unit. In the drying operation unit, a photographic material swollen with water contained in every processing solution during photographic processing is dried as it is transported automatically. In general, hot air is blown upon the swollen material in the drying operation unit in order to remove the water contained therefrom. However, the hot-air drying method has the problem that when drying air is used repeatedly, taking into account the thermal efficiency, the water content in the drying air is increased gradually resulting in protracted drying.
Therefore, a way of drying a photographic material through direct or indirect heating with a heating means is to be considered. For instance, the combined use of hot rollers and drying air has been proposed as the heating means of a drying operation unit. More specifically, the drying operation unit is designed so that the air containing much moisture evaporated from the photographic material heated by a direct heating means (or hot rollers) can be removed from the vicinity of the surface of the photographic material by an indirect heating means (or drying air), thereby accelerating the drying speed. Accordingly, the drying time can be shortened.
In the drying step using hot rollers, a photographic material is, in general, kept traveling linearly, and heated by being held between a pair of hot rollers disposed at part of the traveling course. Further, drying air is blown on the heated photographic material to vaporize the water contained in the heated photographic material.
In the above-described drying process, however, the duration of the contact between the hot roller and the photographic material is very short since the photographic material is transported in the machine direction of the pair of hot rollers. Therefore, raising the temperature of the hot rollers (up to about 100 to 150.degree. C.) is necessary for achieving the intended heating result within the short duration described above. When an operational problem occurs, the hot rollers heated to such a high temperature create a safety hazzard since an operator may want to start maintenance action including repairs as soon as possible. In addition, when there is jamming trouble with the photographic material, the photographic material is overdried at the part near the hot rollers causing a waving phenomenon, thereby losing its utility value. In particular, photographic materials for printing have a very thin support (75 to 100 .mu.m in thickness), so that jamming trouble tends to occur and an undesirable drying result is apt to be produced in an overdried condition. Further, it is necessary to pay careful attention to the overdrying of a photographic material because of the severe requirement for dimensional stability in the graphic arts.
On the other hand, resources, produced gases, waste water, other various wastes, and so on have been reconsidered in many fields from the standpoint of environmental preservation. In the field of photographic processing, there is a growing need for reduction in replenishment rates of processing solutions used for processing photographic materials to save resources, reduce waste water and used vessels, and so on.
However, a reduction in the replenishment rate of a developer retards remarkably the progress of development. Similarly, the fixing speed is markedly decreased by a reduction in the replenishment rate of a fixer. Therefore, these processing solutions are usually replenished with fairly large quantities of replenishers (specifically, 250 to 500 ml of a replenisher for the development of 1 m.sup.2 of photographic material, and 500 to 800 ml of a replenisher for the fixation of 1 m.sup.2 of photographic material). With the intention of accelerating developing speed and fixing speed, each processing temperature is raised and the stirring condition of each processing solution is made more vigorous. These measures, however, cause various troubles such as generation of a bad smell, an increase in the cost of equipment, and so on.
Under these circumstances, it has been strongly desired to develop silver halide photographic materials having high suitability for rapid processing and enabling a reduction in replenishment rates of processing solutions.